1.若(x^m÷x^2n)³÷x^m-n与1/4x²为同类项,且2m+5n=7,求4m²-25n²的值.2.已知a^m × a^n=a^4,a^m÷a^n=a^6,求mn的值.3.已知2^a × 5^b=2^c × d^10,求证:(a-1)(d-1)=(c-1)(b-1).4.计算,当x=一 1/3时,代数式(3x/x-1 - x/x+
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/24 04:47:29
![1.若(x^m÷x^2n)³÷x^m-n与1/4x²为同类项,且2m+5n=7,求4m²-25n²的值.2.已知a^m × a^n=a^4,a^m÷a^n=a^6,求mn的值.3.已知2^a × 5^b=2^c × d^10,求证:(a-1)(d-1)=(c-1)(b-1).4.计算,当x=一 1/3时,代数式(3x/x-1 - x/x+](/uploads/image/z/1654145-17-5.jpg?t=1.%E8%8B%A5%28x%5Em%C3%B7x%5E2n%29%26%23179%3B%C3%B7x%5Em-n%E4%B8%8E1%2F4x%26%23178%3B%E4%B8%BA%E5%90%8C%E7%B1%BB%E9%A1%B9%2C%E4%B8%942m%2B5n%3D7%2C%E6%B1%824m%26%23178%3B-25n%26%23178%3B%E7%9A%84%E5%80%BC.2.%E5%B7%B2%E7%9F%A5a%5Em+%C3%97+a%5En%3Da%5E4%2Ca%5Em%C3%B7a%5En%3Da%5E6%2C%E6%B1%82mn%E7%9A%84%E5%80%BC.3.%E5%B7%B2%E7%9F%A52%5Ea+%C3%97+5%5Eb%3D2%5Ec+%C3%97+d%5E10%2C%E6%B1%82%E8%AF%81%3A%28a-1%29%28d-1%29%3D%28c-1%29%28b-1%29.4.%E8%AE%A1%E7%AE%97%2C%E5%BD%93x%3D%E4%B8%80+1%2F3%E6%97%B6%2C%E4%BB%A3%E6%95%B0%E5%BC%8F%283x%2Fx-1+-+x%2Fx%2B)
1.若(x^m÷x^2n)³÷x^m-n与1/4x²为同类项,且2m+5n=7,求4m²-25n²的值.2.已知a^m × a^n=a^4,a^m÷a^n=a^6,求mn的值.3.已知2^a × 5^b=2^c × d^10,求证:(a-1)(d-1)=(c-1)(b-1).4.计算,当x=一 1/3时,代数式(3x/x-1 - x/x+
1.若(x^m÷x^2n)³÷x^m-n与1/4x²为同类项,且2m+5n=7,求4m²-25n²的值.
2.已知a^m × a^n=a^4,a^m÷a^n=a^6,求mn的值.
3.已知2^a × 5^b=2^c × d^10,求证:(a-1)(d-1)=(c-1)(b-1).
4.计算,当x=一 1/3时,代数式(3x/x-1 - x/x+1)÷x/x²-1的值.
1.若(x^m÷x^2n)³÷x^m-n与1/4x²为同类项,且2m+5n=7,求4m²-25n²的值.2.已知a^m × a^n=a^4,a^m÷a^n=a^6,求mn的值.3.已知2^a × 5^b=2^c × d^10,求证:(a-1)(d-1)=(c-1)(b-1).4.计算,当x=一 1/3时,代数式(3x/x-1 - x/x+
1T
化简得2m-5n=2
因为 2m+5n=7
得 m=9/4 n=1/2
所以25n^2-4m^2=-14
2T
a^m x a^-1=a^4
m-1=4
m=5
a^m/a^n=a^6
m-n=6
n=-1
3T
由已知:2a·5b=2×5 ,∴2a-1·5b-1=1
即 (2a-1·5b-1)^d-1=1^d-1
同理 (2c-1·5d-1)^b-1=1^b-1
∴2^(a-1)(d-1)·5^(b-1)(d-1)
=2^(c-1)(b-1)·5^(d-1)(b-1)
∴2^(a-1)(d-1)=2^(c-1)(b-1)
∴(a-1)(d-1)=(c-1)(b-1)
4T
(3x/x-1-x/x+1)÷x/x^2-1
=[3x(x+1)/(x-1)(x+1)-x(x-1)/(x+1)(x-1)]×(x+1)(x-1)/x
=(3x²+3x-x²+x)/(x+1)(x-1)×(x+1)(x-1)/x
=(2x²+4x)/x
=2x+4
当x=-1/3时
原式=-2/3+4
=10/3